Display module

ABSTRACT

This display module prevents the leakage current generated between a first electrode layer and a second electrode layer that constitute a pixel via an organic light emitting layer and obtains uniform luminance.  
     An interlayer insulation layer ILI is provided between an edge of a first electrode layer AD and an organic light emitting layer OLE that constitute the pixel and the distance between the edge and a second electrode layer CD is secured sufficiently. Further, the interlayer insulation layer ILI is coated with a resin material having fluidity and flatness is improved as a whole. An aperture that accommodates the organic light emitting layer OLE is formed in this interlayer insulation layer ILI and the coated organic light emitting layer OLE is formed in uniform thickness and through a necessary and sufficient spread.

FIELD OF THE INVENTION

[0001] The present invention relates to an active matrix type displaymodule, and, more particularly, to a display module provided with apixel composed of an emitting device, such as an electro luminescenceelement or an LED (light emitting diode) that emits light by applyingthe current to an emitting layer, such as an organic semiconductor thinfilm and a pixel circuit that controls the light emission operation ofthis pixel.

BACKGROUND OF THE INVENTION

[0002] In recent years, with the advent of advanced information society,the demand of a personal computer, a car navigation system, a portableterminal unit, a telecommunications system or these combined products isincreasing. A thin, lightweight, and low power consumption displaydevice is suitable for a display means of these products and a liquidcrystal display module or a display module that uses an electroopticelement, such as a self light emission type EL element or an LED isused.

[0003] The display module that uses the self light emission typeelectrooptic element of the latter is provided with features, such asgood visibility, a wide viewing angle, and suitability for a motionimage display with a fast response, and is assumed to be suitable for animage display in particular.

[0004] A display that uses an organic EL element (also called an organiclight emitting diode, and may also be hereinafter abbreviated to anOLED) of which the emitting layer has organic matter in recent years isgreatly expected as an OLED display in cooperation with a rapidimprovement of luminous efficiency and the progress of networktechnology that enables visual communication. The OLED display has thediode structure in which an organic light emitting layer is sandwichedbetween two electrodes.

[0005] In order to increase the power efficiency in the OLED displayconstituted using such OLED, as described later, an active matrixdriving method in which a thin film transistor (hereinafter referred toas a TFT) is used as a switching element of a pixel is effective.

[0006] An art that drives an OLED display in the active matrix structureis described in Japanese Patent Application Laid-open No. HEI04-328791,Japanese Patent Application Laid-open No. HEI08-241048, or the U.S. Pat.No. 5,550,066, for example, and an art related to a driving voltage isdisclosed in International Publication No. WO98/36407.

[0007] A typical pixel structure of the OLED display has a pixel drivingcircuit (also hereinafter referred to as a pixel circuit) including twoTFTs (the first TFT is a switching transistor and the second TFT is adriver transistor) that are first and second active elements and astorage capacitance (data signal holding element, that is, a capacitor),and this pixel circuit controls the emitting luminance of an OLED. Apixel is arranged in each intersection unit in which M data lines towhich a data line (or an image signal) is supplied and N scanning lines(also hereinafter referred to as gate lines) to which a scanning signalis supplied are arranged in a matrix of N rows multiplied by M columns.

[0008] For the drive of a pixel, a scanning signal (gate signal) issequentially supplied to N rows of gate lines and a switching transistoris set to the on state (turned on). Subsequently, the scanning in thevertical direction is finished once within a one-frame period Tf and aturn-on voltage is re-supplied to the first (first-row) gate line.

[0009] In this driving scheme, the time when the turn-on voltage issupplied to a gate line is less than Tf/N. Usually, about one sixtiethsecond is used as the value of the one-frame period Tf. While theturn-on voltage is being supplied to a certain gate line, all switchingtransistors connected to the data line are set to the on state, and adata voltage (image voltage) is supplied to M columns of data linessimultaneously or sequentially synchronizing with the on state. This isusually used by an active matrix liquid-crystal display.

[0010] A data voltage is stored (held) in a storage capacitance(capacitor) while a turn-on voltage (hereinafter, turn-on is also merelyreferred to as ON. Equally, turn-off is also merely referred to as OFF)is supplied to a gate line, and is kept in almost their value for aone-frame period (or one-field period). The voltage value of the storagecapacitance specifies the gate voltage of a driver transistor.

[0011] Accordingly, the value of the current that flows into the drivertransistor is controlled and light emission of an OLED is controlled.The response time until voltage is applied to the OLED and the lightemission starts is usually less than 1 μs, and even an image (motionimage) of a quick movement can be followed up.

[0012] Incidentally, in an active matrix driving method, because lightemission is performed over a one-frame period, high efficiency isrealized. The difference is clear in comparison with a passive matrixdriving method in which diode electrodes of an OLED are directly coupledto a scanning line and a data line respectively and driven withoutproviding any TFT.

[0013] In the passive matrix driving method, because the current flowsinto the OLED only while the scanning line is being selected.Accordingly, to obtain the same luminance as the light emission of aone-frame period from only the light emission of the short period, theemitting luminance multiplied by almost the number of lines is requiredin comparison with the active matrix driving. To attain the purpose, thedriving voltage and the driving current must inevitably be increased.However, a power consumption loss, such as generation of heat, isincreased and the power efficiency is decreased.

[0014] Thus, the active matrix driving method is assumed to be moresuperior to the passive matrix driving method from the standpoint of areduction in power consumption.

SUMMARY OF THE INVENTION

[0015] In an active matrix driving method of an OLED, when the currentis supplied to a capacitor for holding a display over a one-frameperiod, the one-handed electrode of the capacitor is connected to anoutput terminal of a switching transistor and the other-handed electrodeis connected to a common potential line for the capacitor or a currentsupply line through which the current is supplied to the OLED.

[0016]FIG. 12 is a block diagram for typically describing oneconfiguration example of a conventional display module that uses anOLED, and FIG. 13 is an explanatory drawing of the pixel configurationin FIG. 12. This display module (image display module) is constituted byarranging a data driving circuit DDR, a scanning driving circuit GDR,and a current supply circuit CSS around a display unit AR (insideenclosed by a dotted line in the drawing) formed on a substrate SUBcomposed of an insulating material, such as glass, in a matrix array ofmultiple data lines DLs and multiple gate lines, that is, scanning linesGLs.

[0017] The data driving circuit DDR has a complementary circuitconsisting of N-channel and P-channel type TFTs or a shift registercircuit, a level shifter circuit, and an analog switch circuit composedof a single channel type thin film transistor of only an N channel or aP channel. Besides, the current supply circuit CSS uses only a bus line,and can also be constituted so that the current will be supplied from anexternal power supply.

[0018]FIG. 12 shows a system by which a common potential line COML for acapacitor is provided in the display unit AR, and the other-handedelectrode of the capacitor is connected to this common potential lineCOML. The common potential line COML is drawn out from a terminal COMTof a common potential supply bus line COMB to an external commonpotential source.

[0019] As shown in FIG. 13, a pixel PX has a first thin film transistorTFT 1 that is a switching transistor arranged in the area enclosed by adata line DL and a gate line GL, a second thin film transistor TFT2 thatis a driver transistor, a capacitor CPR, and an organic light emittingdiode OLED. The gate of the thin film transistor TFT1 is connected tothe gate line GL and the drain is connected to the data line DL. Thegate of the thin film transistor TFT2 is connected to the source of thethin film transistor TFT1 and the one-handed electrode (positiveelectrode) is connected to this connection point.

[0020] The drain of the thin film transistor TFT2 is connected to acurrent supply line CSL and the source is connected to an anode AD ofthe organic light emitting diode OLED. The other-handed end (negativeelectrode) of the capacitor CPR is connected to the common supply lineCOML (FIG. 12). The data line DL is driven by the data driving circuitDDR and the scanning line (gate line) GL is driven by the scanningdriving circuit GDR. Further, the current supply line CSL is connectedto the current supply circuit CSS of FIG. 1 via a current supply busline (not shown).

[0021] In FIG. 13, when a pixel PX is selected by the scanning line GLand the thin film transistor TFT1 is turned on, an image signal suppliedfrom the data line DL is stored in the CPR. Further, when the thin filmtransistor TFT1 is turned on, the thin film transistor TFt2 is turnedon, current from the current supply line CSL flows into the OLED, andthis current continues over almost a one-frame period (or a one-fieldperiod, and so forth). The current that flows on this occasion isspecified according to a signal charge stored in the capacitor CPR. Theoperation level of the capacitor CPR is specified according to thepotential of the common potential line COML. Accordingly, the lightemission of the pixel is controlled.

[0022] Because this system needs to provide the common potential lineCOML by piercing through part of a pixel region, what is called anaperture ratio is decreased and the improvement of brightness as a wholedisplay module will be suppressed. Further, the number of productionprocesses for providing the common potential line COML is increased.

[0023]FIG. 14 is the same block diagram for typically describing anotherconfiguration example of a conventional display module that uses anOLED. In this example, the basic placement of the thin film transistorsTFT1, TFT2 and the capacitor CPR that constitute each pixel is the samedisplacement as FIG. 13, but differs in that the other end of thecapacitor CPR is connected to the current supply line CSL.

[0024] That is, when a pixel PX is selected by the scanning line GL andthe thin film transistor TFT1 is turned on, an image signal suppliedfrom the data line DL is stored in the capacitor CPR. If the thin filmtransistor TFT2 is turned on when the thin film transistor TFT1 isturned off, the current from the current supply line CSL flows into theOLED. This current continues over almost a one-frame period in the samemanner as FIG. 13. The current that flows on this occasion is specifieda signal charge stored in the capacitor CPR. The operation level of thecapacitor CPR is specified according to the potential of the currentsupply line CSL. Accordingly, the light emission of a pixel iscontrolled.

[0025] In this type of the display module described in FIGS. 12 to 14,the source electrode of the thin film transistor TFT2 that forms a firstelectrode layer (for example, anode) AD of the organic light emittingdiode OLED is formed using a conductive thin film, such as ITO (indiumtin oxide), and the first electrode layer AD of each pixel PX isisolated individually. Accordingly, an electric field is concentrated onan edge of the first electrode layer AD and the leakage current may begenerated between the edge and a second electrode layer (for example,cathode) CD.

[0026]FIG. 15 is a sectional view for describing the structure near apixel of a display module that uses an organic light emitting diode.This display module is constituted by piling up a polycrystallinesilicon semiconductor layer PSI that uses low temperaturepolycrystalline silicon as an ideal material, a first insulation layerIS1, a gate line (gate electrode) GL that is a scanning line, a secondinsulation layer IS2, a source electrode SD formed using an aluminumwire, a third insulation layer IS3, a passivation film PSV, a firstelectrode layer AD, an organic light emitting layer OLE, and a secondelectrode layer CD on a glass substrate SUB.

[0027] When a thin film transistor (this thin film transistor is adriver transistor) composed of the polycrystalline silicon semiconductorlayer PSI, the gate line GL, and the source electrode SD is selected, anorganic light emitting diode formed using the first electrode layer ADconnected to the source electrode SD, the organic light emitting layerOLE, and the second electrode layer CD emits light and the light L isincident on the outside from the substrate SUB.

[0028] In the configuration part of this organic light emitting diode,the edge of the first electrode layer AD or the edge of the secondelectrode layer CD is close to the second electrode layer CD or thefirst electrode layer AD via the thin organic light emitting layer OLE.In such structure, the following problem is easy to occur.

[0029]FIG. 16 is an enlarged drawing of the part shown by the A of FIG.15. As shown in the same drawing, an electric field is concentrated onthe edge of the first electrode layer AD or the second electrode layerCD. Accordingly, the organic light emitting layer OLE is dielectricallybroken down between the second electrode layer CD and the firstelectrode layer AD and leakage current X is easy to occur. When suchleakage current X occurs, a high current flows from the current supplyline CSL into a thin film transistor and will damage the thin filmtransistor. When the thin film transistor is damaged, what is called apoint defect occurs and a display fault will be produced.

[0030] Further, because a scanning line, a data line or two thin filmtransistors, and a capacitor are formed on a substrate SUB in amulti-layered structure, even if the top of the second electrode layercoated with the organic light emitting layer is flat, the flatness ofthe periphery is extremely low. Therefore, dispersion occurs in thespace between the first electrode layer and the second electrode layer,and the same leakage current as above occurs in the part where bothelectrode layers are adjacent each other.

[0031] An organic light emitting layer is coated using a method, such asprinting coating, coating using ink jet, or spin coating. Because thecoating material of the organic light emitting layer used in suchcoating has fluidity, if the flatness of a coating surface and itsperiphery is low, the coated organic emitting material flows into theperiphery or is piled up in a part of the periphery. Accordingly, it isdifficult to form the organic light emitting layer in uniform thicknessand through a necessary and sufficient spread over the predeterminedpixel region.

[0032] When an organic light emitting layer differs in its thickness andspread every pixel, a difference occurs in each emitting luminance andthe brightness in all screen areas becomes uneven, thereby disablingacquisition of a high image quality display.

[0033] An object of the present invention is to provide a display modulethat enables a high quality display by preventing the leakage currentgenerated between a first electrode layer and a second electrode layerthat constitute a pixel via an organic light emitting layer and formingthe organic light emitting layer that constitutes the pixel in uniformthickness and through a necessary and sufficient spread over thepredetermined pixel region.

[0034] To attain the above object, the present invention prevents thegeneration of leakage current between a first electrode layer and asecond electrode layer, as described above, by providing an interlayerinsulation layer between an edge of the first electrode layer and anorganic light emitting layer that constitute a pixel and sufficientlysecuring the distance between the edge and the second electrode layer.

[0035] Further, the present invention improves flatness as a whole byusing a resin material with fluidity in the interlayer insulation layer,forming an organic light emitting layer accommodation unit on thisinterlayer insulation layer, and forming the coated organic lightemitting layer in uniform thickness and through a necessary andsufficient spread over the predetermined pixel region.

[0036] By using this configuration, the leakage current that isgenerated between a first electrode layer and a second electrode layerthat constitute a pixel via an organic light emitting layer isprevented. Further, because the organic light emitting layer thatconstitutes the pixel is formed in uniform thickness and through anecessary and sufficient spread over the predetermined pixel region, adisplay module that enables a high quality display can be obtained. Amore specific configuration example of the present invention isdescribed below. That is,

[0037] (1) A display module is provided with multiple scanning linesarranged in a matrix on a substrate, multiple data lines that intersectthe multiple scanning lines, and a current supply line that suppliesdisplay current to a pixel and has a pixel every intersection unit ofeach of the scanning lines and each of the data lines, wherein

[0038] the pixel has an active element selected by the scanning line, adata holding element that holds a data signal supplied from the dataline by the turn-on of this active element, and an emitting device thatemits light by the current supplied from the current supply line inaccordance with the data signal held by the data holding element,

[0039] the emitting device has a first electrode layer driven by theactive element, an organic light emitting layer applied on the firstelectrode layer, and a second electrode layer formed on the organiclight emitting layer, and

[0040] an interlayer insulation layer is provided between the firstelectrode layer and the second electrode layer in the periphery of alight emission unit formed in the lamination structure of the firstelectrode layer, the organic light emitting layer, and the secondelectrode layer.

[0041] (2) In (1), the interlayer insulation layer provides an aperturein which the organic light emitting layer is accommodated in the coatingregion of the organic light emitting layer that constitutes the lightemission unit.

[0042] (3) In (2), the interlayer insulation layer is formed by beingcoated with a fluidity resin.

[0043] (4) In (3), an acrylic resin is used as the fluidity resin.

[0044] (5) In any one of (1) to (4), the display module has at leasteither an insulation layer or a passivation film between at least a partof the first electrode layer and the substrate, and an aperture in whichthe organic light emitting layer is accommodated in at least either theinsulation layer or the passivation film.

[0045] (6) In any one of (1) to (5), the interlayer insulation layer isformed by covering an edge of the first electrode layer.

[0046] (7) In (6), the interlayer insulation layer is formed by coveringall edges of the first electrode layer.

[0047] By using the above configuration of (1) to (7), the distancebetween the edge of the first electrode layer and the edge of the secondelectrode layer is secured sufficiently and the generation of leakagecurrent between the first electrode layer and the second electrode layeris prevented via an organic light emitting layer.

[0048] (8) A display module is provided with multiple scanning linesarranged in a matrix on a substrate, multiple data lines that intersectthe multiple scanning lines, and a current supply line that suppliesdisplay current to the pixel and has a pixel every intersection unit ofeach of the scanning lines and each of the data lines, wherein

[0049] the pixel has an active element selected by the scanning line, adata holding element that holds a data signal supplied from the dataline by the turn-on of this active element, and an emitting device thatemits light by the current supplied from the current supply line inaccordance with the data signal held by the data holding element,

[0050] the emitting device has a first electrode layer driven by theactive element, an organic light emitting layer applied on the firstelectrode layer, and a second electrode layer formed on the organiclight emitting layer, and

[0051] an interlayer insulation layer formed by coating a fluidity resinis provided between the first electrode layer and the second electrodelayer in the periphery of a light emission unit formed in the laminationstructure of the first electrode layer, the organic light emittinglayer, and the second electrode layer.

[0052] (9) In (8), an acrylic resin is used as the fluidity resin.

[0053] (10) In (8) or (9), the interlayer insulation layer is formed bycovering an edge of the first electrode layer.

[0054] (11) The interlayer insulation layer is formed by covering alledges of the first electrode layer.

[0055] (12) In any one of (8) to (1), the first electrode layer isformed using ITO.

[0056] By using the above configuration of (8) to (12), because anorganic light emitting layer that constitutes a pixel is formed inuniform thickness and through a necessary and sufficient spread over thepredetermined pixel region in addition to the effect according to theabove configuration of (1) to (7), a display module that enables a highquality display can be obtained.

[0057] Besides, the present invention is not limited to the aboveconfiguration and the configuration of the embodiments described later,and, needless to say, enables various modifications without deviatingfrom a technical idea of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0058] Preferred embodiments of the present invention will be describedin detail based on the followings, wherein:

[0059]FIG. 1 is a typical sectional view near a pixel for describing theconfiguration of a first embodiment of a display module according to thepresent invention;

[0060]FIG. 2 is a typical drawing for describing a cross section near apixel in the order of a production process in which an example of theproduction process of the display module of the first embodiment isdescribed in the display module according to the present invention;

[0061]FIG. 3 is a typical drawing in the vicinity of a pixel fordescribing a light emission mechanism of the display module according tothe present invention;

[0062]FIG. 4 is a typical sectional view in the vicinity a pixel fordescribing the configuration of a second embodiment of the displaymodule according to the present invention;

[0063]FIG. 5 is a typical sectional view in the vicinity a pixel fordescribing the configuration of a third embodiment of the display moduleaccording to the present invention;

[0064]FIG. 6 is a typical sectional view in the vicinity a pixel fordescribing the configuration of a fourth embodiment of the displaymodule according to the present invention;

[0065]FIG. 7 is a top plan view near a pixel for describing an exampleof the circuit configuration of the display module according to thepresent invention;

[0066]FIG. 8 is a typical sectional view in the vicinity a pixel fordescribing the configuration of a fifth embodiment of the display moduleaccording to the present invention;

[0067]FIG. 9 is a top plan view near a pixel for describing an exampleof the circuit configuration of the display module according to thepresent invention shown in FIG. 8;

[0068]FIG. 10 is a top plan view for typically describing an example ofthe circuit placement of the display module according to the presentinvention;

[0069]FIG. 11 is a top plan view for typically describing an example ofthe aperture position of a pixel provided corresponding to the circuitplacement of FIG. 10;

[0070]FIG. 12 is a block diagram for typically describing aconfiguration example of a conventional display module using an organicemitting device;

[0071]FIG. 13 is an explanatory drawing of the pixel configuration inFIG. 12;

[0072]FIG. 14 is the same block diagram as FIG. 13 for typicallydescribing another configuration example of the conventional displaymodule that uses the organic emitting device;

[0073]FIG. 15 is a sectional view for describing the structure in thevicinity of a pixel of a display module that uses the organic emittingdevice; and

[0074]FIG. 16 is an enlarged drawing of the part showing by A of FIG.15.

DESCRIPTION OF PREFERRED EMBODIMENTS

[0075] Embodiments of the present invention are described in detailbelow with reference to the drawings of the embodiments.

[0076] An organic light emitting layer provided in each pixel that isnot shown, but is described later performs a monochromatic or colordisplay by emitting light in the luminance that is proportional to acurrent value and a color (including white) that depends on the organicmaterials and performs the color display that emits by combining a colorfilter, such as red, green, or blue with an organic layer that emitswhite light.

[0077]FIG. 1 is a typical sectional view near a pixel for describing theconfiguration of a first example of a display module according to thepresent invention. The display module that uses an active matrix typeorganic light emitting diode (OLED) shown in FIG. 1 has a thin filmtransistor of each element formed on an insulating substrate SUB, suchas glass, using a polycrystalline silicon layer PSI.

[0078] The thin film transistor of this embodiment has a firstinsulation layer IS1, a gate line (scanning line) GL, a secondinsulation layer IS2, a source line SD, and a third insulation layer IS3on the polycrystalline silicon layer PSI, and an ITO pattern thatbecomes a first electrode layer is formed on a passivation film PSVformed on the upper layer unit of the third insulation layer IS3. Thisfirst electrode layer AD is connected to the source line SD through acontact hole perforated by piercing into the passivation film PSV andthe third layer IS3.

[0079] Subsequently, before an organic light emitting layer OLE iscoated on the passivation film OSV, an interlayer insulation layer ILIwith fluidity composed of an acrylic resin is coated and the smoothnessof the surface is improved. At the same time, an aperture is formed inthe pixel region of the interlayer insulation layer ILI by a processingmeans, such as a photolithographic technique. This aperture is formedonly in the area required for providing an organic light emitting layerinside the pattern of the first electrode layer AD.

[0080] Accordingly, a recessed part in which the interlayer insulationlayer ILI becomes an inside wall having a taper and a flat firstelectrode layer AD is exposed at the bottom is formed in the pixelregion. By coating this recessed part with an organic light emittinglayer OLE, a uniform organic light emitting layer OLE in necessarythickness is accommodated and formed in the pixel region. Further, theorganic light emitting layer OLE coated around the pixel region isisolated from the first electrode layer AD in the interlayer insulationlayer ILI.

[0081] After the organic light emitting layer is coated, the upper layeris covered and a second electrode layer CD is formed. A metal film issuitable for this second electrode layer CD. Because the interlayerinsulation layer ILI has a taper, what is called step disconnection isdifficult to occur in the organic light emitting layer OLE and thesecond electrode layer CD applied on it. The second electrode layer CDformed at an edge around the organic light emitting layer OLE isisolated from the first electrode layer AD including the edge.Accordingly, the generation of leakage current between the edge ofeither the first electrode layer AD or the second electrode layer CD orbetween the edge of both electrode layers is prevented sufficiently.

[0082] Thus, according to this embodiment, the distance between an edgeof a first electrode layer and a second electrode layer that constitutea pixel is secured sufficiently and the generation of leakage currentbetween the first electrode and the second electrode layer via anorganic light emitting layer is prevented. Further, because the organiclight emitting layer that constitutes the pixel is formed in uniformthickness and through a necessary and sufficient spread over thepredetermined pixel region a display module that enables a high qualitydisplay is obtained.

[0083]FIG. 2 is a typical drawing for describing a cross section near apixel in the order of a production process in which an example of theproduction process of the display module of the first embodiment isdescribed in the display module according to the present invention. Thisembodiment uses a thin film transistor of what is called the top gatestructure, but also uses a thin film transistor of what is called thebottom gate structure in the same manner. This process is describedbelow in the order of steps (1) to (11).

[0084] (1) A polycrystalline silicon semiconductor layer PSI ispatterned on a glass substrate SUB and laser annealing forcrystallization is applied.

[0085] (2) A first insulation layer IS1 is formed on it.

[0086] (3) A gate line (scanning line) GL is formed by depositing andpatterning a conductive thin film, such as titanium (Ti) or tungsten(W).

[0087] (4) A second insulation layer IS2 is formed and a contact hole isperforated at a necessary place.

[0088] (5) An aluminum wire that becomes a source electrode SD is formed(as the need arises, the top and bottom of an aluminum thin film aresandwiched between materials of titanium (Ti) or tungsten (W).

[0089] (6) A third insulation layer IS3 is formed by covering analuminum wire.

[0090] (7) Further, a passivation film PSV is formed using p-Sin. Acontact hole that pierces into this passivation film PSV and the thirdinsulation layer IS3 and reaches the source electrode SD is perforated.

[0091] (8) A first electrode AD is formed by depositing ITO. This firstelectrode layer AD is connected to the source electrode SD via thecontact hole.

[0092] (9) An interlayer insulation layer ILI for insulating an organiclight emitting layer from an edge of the first electrode layer AD isformed. Further, an aperture is perforated in the pixel region requiredfor light emission and at a place necessary for external connection inthe interlayer insulation layer ILI. The interlayer insulation layer ILIuses an acrylic resin with fluidity. A taper is formed on an inside wallby applying heat when the aperture pattern of the pixel region isformed.

[0093] (10) The aperture of the pixel region is coated with an organiclight emitting layer OLE. The coating of the organic light emittinglayer OLE is performed by a method, such as mask printing or ink jet.

[0094] (11) A metal layer is formed by covering an organic lightemitting layer OLE and a second electrode layer CD.

[0095] After the above process, a display module is completed by beingsealed in a sealing can or with a proper member, such as glass andceramics, and being put into a module.

[0096]FIG. 3 is a typical drawing in the vicinity of a pixel fordescribing a light emission mechanism of the display module according tothe present invention. The same reference symbol as FIG. 1 correspondsto the same part. Further, the arrow mark using the reference symbol Iof the drawing shows a path of the current that yields to lightemission.

[0097] A thin film transistor TFT is a driver transistor. When this thinfilm transistor TFT is selected by a gate line GL, the current I havinga current value of a gray scale that matches a data signal held in acapacitor is supplied to a first electrode layer AD of an organic lightemitting diode OLED through the thin film transistor TFT (see FIG. 14).

[0098] In an organic light emitting diode OLED, an electron from asecond electrode layer CD and a hole from a first electrode layer AD arerecombined in the organic light emitting layer OLE and light L of aspectrum that matches material characteristics of the organic lightemitting layer OLE is emitted. The first electrode layer AD isindependent every pixel and the second electrode layer is formed allover in a film shape concerning all pixels.

[0099] The current that passes through an organic emitting device OEfrom a thin film transistor TFT flows out via a current drain line thatis not shown from a second electrode layer CD. A two-dimensional displaymodule is constituted by arranging such many pixels in a matrix.

[0100]FIG. 4 is a typical sectional view near a pixel for describing theconfiguration of the second example of the display module according tothe present invention. The same reference symbol as FIG. 1 correspondsto the same function part. In this embodiment, the film thickness of theinterlayer insulation layer ILI shown in FIG. 1 is about 1 μm, whereasthe volume of an aperture (recessed part) in which an organic lightemitting layer OLE is accommodated is increased by thickening the filmthickness 2 or 3 μm, for example.

[0101] This embodiment has the structure suitable when an organic lightemitting layer OLE is coated using an inkjet system. When the organiclight emitting layer OLE is coated using the inkjet system, an organicemitting material splashes from an inkjet nozzle into the aperture of aninterlayer insulation layer and reaches a first electrode layer AD withthe material diluted in some solvent and with the volume increased.

[0102] On this occasion, because the volume of an aperture is increased(deepened), a color mixture of both apertures of adjacent pixels can beprevented. Moreover, the color mixture into the adjacent pixels canfurther be prevented effectively by smoothing the tapered angle of aninside wall that forms the aperture of an interlayer insulation layer.

[0103] That is, according to this embodiment, an organic light emittinglayer applied to each pixel can be isolated clearly and deterioration inthe saturation of a luminous color can be prevented in addition to theeffect of the embodiment described above. Besides, mask printing andspin coating systems as well as an inkjet system can be applied to thecoating of the organic light emitting layer OLE.

[0104]FIG. 5 is a typical sectional view near a pixel for describing theconfiguration of a third example of the display module according to thepresent invention. The same reference symbol as FIG. 1 corresponds tothe same function part. This embodiment further increases the volume ofan aperture (recessed part) in which the insulation layer IS and thepassivation film PSV are removed from the pixel region and an organiclight emitting layer OLE is accommodated.

[0105] The interlayer insulation layer ILI is formed in the inside wallof the recessed part that is an aperture. The insulation layer of anorganic light emitting layer OLE is formed on a first electrode AD andopens at the bottom of the recessed part. The organic light emittinglayer OLE is accommodated in this aperture and the second electrodelayer CD is formed on it.

[0106] This embodiment is also suitable when an organic light emittinglayer OEL is coated using an inkjet system and, in addition to theeffect of the example, an organic light emitting layer applied to eachpixel can be isolated clearly and deterioration in the saturation of aluminous color can be prevented. Besides, mask printing and spin coatingsystems as well as the inkjet system can be applied to the coating ofthe organic light emitting layer OLE.

[0107]FIG. 6 is a typical sectional view near a pixel for describing theconfiguration of a fourth embodiment of the display module according tothe present invention. The same reference symbol as FIG. 1 correspondsto the same function part. In this embodiment, a second passivation filmPSV2 is further formed on a passivation film PSV (equals to a firstpassivation film PSV1) in the first embodiment described in FIG. 1.Another configuration is the same configuration as FIG. 1.

[0108] In this embodiment, in addition to the effect of the firstembodiment, because the top layer is further flatten and the intrusionof an external gas and moisture is prevented more accurately, thereliability of a display module can be improved further. Besides, thesecond passivation film PSV2 can also be formed toward the second orthird embodiments in the same manner.

[0109]FIG. 7 is a top plain view near a pixel for describing an exampleof the circuit configuration of the display module according to thepresent invention. A pixel is formed in the area enclosed by a scanningline (gate line) GL and a data line DL. Besides, the reference symbol ADis a first electrode layer (anode here) and CSL is a current supplyline.

[0110] A pixel circuit has a first thin film transistor TFT1 (switchingtransistor), a second thin film transistor TFT2 (driver transistor), anda capacitor CPR. Further, an aperture DE that accommodates an organiclight emitting layer is provided in the part where the pixel circuit andeach wiring are prevented.

[0111]FIG. 8 is a typical sectional view for describing theconfiguration of a fifth embodiment of the circuit configuration of thedisplay module according to the present invention. The same referencesymbol as FIG. 1 corresponds to the same function part. This embodimenthas the configuration in which the exit direction of light emission isset at the opposite side with a substrate. In the drawing, CD′ indicatesa first electrode layer (cathode here) formed using a metal thin filmand AD′ indicates a second electrode (anode here) formed using atransparent conductive film, such as ITO.

[0112] In this embodiment, the emission light in an organic lightemitting layer OLE exits from the second electrode layer AD′.Accordingly, a sealing member that is not shown, but is provided on theside of the second electrode layer AD′ uses a transparent member, suchas glass.

[0113]FIG. 9 is a top plan drawing near a pixel for describing anexample of the circuit configuration of the display module according tothe present invention shown in FIG. 8. The same reference symbol as FIG.7 corresponds to the same function part. A pixel is formed in the areaenclosed by a scanning line (gate line) GL and a data line DL in thesame manner as the above embodiment.

[0114] In this embodiment, an aperture DE that accommodates an organiclight emitting layer OLE needs not to be provided in the part where thepixel circuit and each wiring are prevented. Accordingly, because theconfiguration of this embodiment is obtained, there is an advantage thata pixel having a high aperture ratio and a wide area can be formed. Onthe whole, a display module having a bright screen, and a display modulehaving low consumption power and a long life span can be obtained.

[0115]FIG. 10 is a top plan drawing for typically describing an exampleof the circuit placement of the display module according to the presentinvention, and FIG. 11 is a top plan view for typically describing anexample of the aperture position of a pixel provided corresponding tothe circuit placement of FIG. 10. Each pixel is formed in the partenclosed by a scanning line GL driven in a scanning driving circuit GDRand a data line DL driven in a data driving circuit DDR and arranged ina matrix shape. A current supply line CSL branches at the outside of adisplay region AR from a current supply bus line CSB and arranged inparallel to the data line DL for each pixel.

[0116] Besides, PAD is a pad for externally supplying a signal and powerto a display module via a flexible printed board. PAD1 indicates a padfor a data driver, PAD2 indicates a pad for a scanning driver, and PAD3indicates a current supply pad. Even each part of these pads forms anaperture in an insulation layer and a passivation film.

[0117] The aperture for applying an organic light emitting layer thatconstitutes the light emission area of a pixel is arranged in a matrixshape corresponding to each pixel as shown in FIG. 11. Further, thereliability of a display module is improved by also providing anaperture unit in a sealing unit that turns around a display region AR asthe need arises and improving the adhesion between a substrate and thesealing unit. Besides, an aperture that is a contact hole for connectinga second electrode layer to the bottom wiring layer is also formed.

[0118] Besides, the present invention is not limited to a display modulethat uses the OLED described above, and can also be applied to anotherdisplay module that performs a display in the same light emissionoperation as the OLED.

[0119] As described above, according to the present invention, becausethe leakage current generated between a first electrode layer and asecond electrode layer that constitute a pixel via an organic lightemitting layer is prevented and the organic light emitting layer thatconstitutes the pixel is formed in uniform thickness and through anecessary and sufficient spread over the predetermined pixel region, adisplay module that enables a high quality display can be provided.

What is claimed is:
 1. A display module, comprising: multiple scanninglines arranged on a substrate in a matrix, multiple data lines thatintersect said multiple scanning lines, and a current supply line thatsupplies a display current to a pixel; and a pixel every intersectionunit of each of said scanning lines and each of said data lines, whereinsaid pixel comprises an active element selected by said scanning line, adata holding element that holds a data signal supplied from said dataline by the turn-on of said active element, and an emitting device thatemits light in the current supplied from said current supply line inaccordance with the data signal supplied from said current supply line;said emitting device comprises a first electrode layer driven by saidactive element, an organic light emitting layer applied on said firstelectrode layer, and a second electrode layer formed on said organiclight emitting layer; and an interlayer insulation layer between saidfirst electrode layer and said second electrode layer in the peripheryof a light emission unit formed in the lamination structure of saidfirst electrode layer, said organic light emitting layer, and saidsecond electrode layer.
 2. The display module according to claim 1,wherein said interlayer insulation layer forms an aperture in which saidorganic light emitting layer is accommodated in a coating region of saidorganic light emitting layer that constitutes said light emission unit.3. The display module according to claim 1, wherein said interlayerinsulation layer is formed by being coated with a fluidity resin.
 4. Thedisplay module according to claim 1, wherein said interlayer insulationlayer is formed by being coated with an acrylic resin.
 5. The displaymodule according to claim 1, further comprising either an insulationlayer or a passivation film between at least a part of said firstelectrode layer and said substrate, wherein at least either saidinsulation layer or said passivation film comprises an aperture thataccommodates said organic light emitting layer.
 6. The display moduleaccording to claim 1, wherein said interlayer insulation layer is formedby covering an edge of said first electrode layer.
 7. The display moduleaccording to claim 1, wherein said interlayer insulation layer is formedby covering all edges of said first electrode layer.
 8. A displaymodule, comprising: multiple scanning lines arranged on a substrate in amatrix, multiple data lines that intersect said multiple scanning lines,and a current supply line that supplies a display current to said pixel;and a pixel every intersection unit of each of said scanning lines andeach of said data lines, wherein said pixel comprises an active elementselected by the scanning line, a data holding element that holds a datasignal supplied from said data line by the turn-on of said activeelement, and an emitting device that emits light in the current suppliedfrom said current supply line in accordance with the data signal held bysaid data holding element line; said emitting device comprises a firstelectrode layer driven by the active element, an organic light emittinglayer applied on said first electrode layer, and a second electrodelayer formed on said organic light emitting layer; and an interlayerinsulation layer formed by being coated with a fluidity resin betweensaid first electrode layer and said second electrode layer in theperiphery of a light emission unit formed in the lamination structure ofsaid first electrode layer, said organic light emitting layer, and saidsecond electrode layer.
 9. The display module according to claim 8,wherein said interlayer insulation layer is formed by being coated withan acrylic resin.
 10. The display module according to claim 8, whereinsaid interlayer insulation layer is formed by covering an edge of saidfirst electrode layer.
 11. The display module according to claim 8,wherein said interlayer insulation layer is formed by covering all edgesof said first electrode layer.
 12. The display module according to claim8, wherein said first electrode layer is formed using ITO.